1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 #include "coretypes.h"
30 #include "insn-config.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
45 #ifndef HAVE_conditional_execution
46 #define HAVE_conditional_execution 0
48 #ifndef HAVE_conditional_move
49 #define HAVE_conditional_move 0
60 #ifndef HAVE_conditional_trap
61 #define HAVE_conditional_trap 0
64 #ifndef MAX_CONDITIONAL_EXECUTE
65 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
68 #define NULL_EDGE ((edge) NULL)
69 #define NULL_BLOCK ((basic_block) NULL)
71 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
72 static int num_possible_if_blocks
;
74 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
76 static int num_updated_if_blocks
;
78 /* # of changes made which require life information to be updated. */
79 static int num_true_changes
;
81 /* Whether conditional execution changes were made. */
82 static int cond_exec_changed_p
;
84 /* True if life data ok at present. */
85 static bool life_data_ok
;
87 /* Forward references. */
88 static int count_bb_insns (basic_block
);
89 static bool cheap_bb_rtx_cost_p (basic_block
, int);
90 static rtx
first_active_insn (basic_block
);
91 static rtx
last_active_insn (basic_block
, int);
92 static basic_block
block_fallthru (basic_block
);
93 static int cond_exec_process_insns (ce_if_block_t
*, rtx
, rtx
, rtx
, rtx
, int);
94 static rtx
cond_exec_get_condition (rtx
);
95 static int cond_exec_process_if_block (ce_if_block_t
*, int);
96 static rtx
noce_get_condition (rtx
, rtx
*);
97 static int noce_operand_ok (rtx
);
98 static int noce_process_if_block (ce_if_block_t
*);
99 static int process_if_block (ce_if_block_t
*);
100 static void merge_if_block (ce_if_block_t
*);
101 static int find_cond_trap (basic_block
, edge
, edge
);
102 static basic_block
find_if_header (basic_block
, int);
103 static int block_jumps_and_fallthru_p (basic_block
, basic_block
);
104 static int find_if_block (ce_if_block_t
*);
105 static int find_if_case_1 (basic_block
, edge
, edge
);
106 static int find_if_case_2 (basic_block
, edge
, edge
);
107 static int find_memory (rtx
*, void *);
108 static int dead_or_predicable (basic_block
, basic_block
, basic_block
,
110 static void noce_emit_move_insn (rtx
, rtx
);
111 static rtx
block_has_only_trap (basic_block
);
112 static void mark_loop_exit_edges (void);
114 /* Sets EDGE_LOOP_EXIT flag for all loop exits. */
116 mark_loop_exit_edges (void)
122 flow_loops_find (&loops
, LOOP_TREE
);
123 free_dominance_info (CDI_DOMINATORS
);
130 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
132 if (find_common_loop (bb
->loop_father
, e
->dest
->loop_father
)
134 e
->flags
|= EDGE_LOOP_EXIT
;
136 e
->flags
&= ~EDGE_LOOP_EXIT
;
141 flow_loops_free (&loops
);
144 /* Count the number of non-jump active insns in BB. */
147 count_bb_insns (basic_block bb
)
150 rtx insn
= BB_HEAD (bb
);
154 if (CALL_P (insn
) || NONJUMP_INSN_P (insn
))
157 if (insn
== BB_END (bb
))
159 insn
= NEXT_INSN (insn
);
165 /* Determine whether the total insn_rtx_cost on non-jump insns in
166 basic block BB is less than MAX_COST. This function returns
167 false if the cost of any instruction could not be estimated. */
170 cheap_bb_rtx_cost_p (basic_block bb
, int max_cost
)
173 rtx insn
= BB_HEAD (bb
);
177 if (NONJUMP_INSN_P (insn
))
179 int cost
= insn_rtx_cost (PATTERN (insn
));
183 /* If this instruction is the load or set of a "stack" register,
184 such as a floating point register on x87, then the cost of
185 speculatively executing this instruction needs to include
186 the additional cost of popping this register off of the
190 rtx set
= single_set (insn
);
191 if (set
&& STACK_REG_P (SET_DEST (set
)))
192 cost
+= COSTS_N_INSNS (1);
197 if (count
>= max_cost
)
200 else if (CALL_P (insn
))
203 if (insn
== BB_END (bb
))
205 insn
= NEXT_INSN (insn
);
211 /* Return the first non-jump active insn in the basic block. */
214 first_active_insn (basic_block bb
)
216 rtx insn
= BB_HEAD (bb
);
220 if (insn
== BB_END (bb
))
222 insn
= NEXT_INSN (insn
);
225 while (NOTE_P (insn
))
227 if (insn
== BB_END (bb
))
229 insn
= NEXT_INSN (insn
);
238 /* Return the last non-jump active (non-jump) insn in the basic block. */
241 last_active_insn (basic_block bb
, int skip_use_p
)
243 rtx insn
= BB_END (bb
);
244 rtx head
= BB_HEAD (bb
);
249 && NONJUMP_INSN_P (insn
)
250 && GET_CODE (PATTERN (insn
)) == USE
))
254 insn
= PREV_INSN (insn
);
263 /* Return the basic block reached by falling though the basic block BB. */
266 block_fallthru (basic_block bb
)
271 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
272 if (e
->flags
& EDGE_FALLTHRU
)
275 return (e
) ? e
->dest
: NULL_BLOCK
;
278 /* Go through a bunch of insns, converting them to conditional
279 execution format if possible. Return TRUE if all of the non-note
280 insns were processed. */
283 cond_exec_process_insns (ce_if_block_t
*ce_info ATTRIBUTE_UNUSED
,
284 /* if block information */rtx start
,
285 /* first insn to look at */rtx end
,
286 /* last insn to look at */rtx test
,
287 /* conditional execution test */rtx prob_val
,
288 /* probability of branch taken. */int mod_ok
)
290 int must_be_last
= FALSE
;
298 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
303 if (!NONJUMP_INSN_P (insn
) && !CALL_P (insn
))
306 /* Remove USE insns that get in the way. */
307 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
309 /* ??? Ug. Actually unlinking the thing is problematic,
310 given what we'd have to coordinate with our callers. */
311 SET_INSN_DELETED (insn
);
315 /* Last insn wasn't last? */
319 if (modified_in_p (test
, insn
))
326 /* Now build the conditional form of the instruction. */
327 pattern
= PATTERN (insn
);
328 xtest
= copy_rtx (test
);
330 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
332 if (GET_CODE (pattern
) == COND_EXEC
)
334 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
337 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
338 COND_EXEC_TEST (pattern
));
339 pattern
= COND_EXEC_CODE (pattern
);
342 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
344 /* If the machine needs to modify the insn being conditionally executed,
345 say for example to force a constant integer operand into a temp
346 register, do so here. */
347 #ifdef IFCVT_MODIFY_INSN
348 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
353 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
355 if (CALL_P (insn
) && prob_val
)
356 validate_change (insn
, ®_NOTES (insn
),
357 alloc_EXPR_LIST (REG_BR_PROB
, prob_val
,
358 REG_NOTES (insn
)), 1);
368 /* Return the condition for a jump. Do not do any special processing. */
371 cond_exec_get_condition (rtx jump
)
375 if (any_condjump_p (jump
))
376 test_if
= SET_SRC (pc_set (jump
));
379 cond
= XEXP (test_if
, 0);
381 /* If this branches to JUMP_LABEL when the condition is false,
382 reverse the condition. */
383 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
384 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
386 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
390 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
397 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
398 to conditional execution. Return TRUE if we were successful at
399 converting the block. */
402 cond_exec_process_if_block (ce_if_block_t
* ce_info
,
403 /* if block information */int do_multiple_p
)
405 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
406 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
407 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
408 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
409 rtx then_start
; /* first insn in THEN block */
410 rtx then_end
; /* last insn + 1 in THEN block */
411 rtx else_start
= NULL_RTX
; /* first insn in ELSE block or NULL */
412 rtx else_end
= NULL_RTX
; /* last insn + 1 in ELSE block */
413 int max
; /* max # of insns to convert. */
414 int then_mod_ok
; /* whether conditional mods are ok in THEN */
415 rtx true_expr
; /* test for else block insns */
416 rtx false_expr
; /* test for then block insns */
417 rtx true_prob_val
; /* probability of else block */
418 rtx false_prob_val
; /* probability of then block */
420 enum rtx_code false_code
;
422 /* If test is comprised of && or || elements, and we've failed at handling
423 all of them together, just use the last test if it is the special case of
424 && elements without an ELSE block. */
425 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
427 if (else_bb
|| ! ce_info
->and_and_p
)
430 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
431 ce_info
->num_multiple_test_blocks
= 0;
432 ce_info
->num_and_and_blocks
= 0;
433 ce_info
->num_or_or_blocks
= 0;
436 /* Find the conditional jump to the ELSE or JOIN part, and isolate
438 test_expr
= cond_exec_get_condition (BB_END (test_bb
));
442 /* If the conditional jump is more than just a conditional jump,
443 then we can not do conditional execution conversion on this block. */
444 if (! onlyjump_p (BB_END (test_bb
)))
447 /* Collect the bounds of where we're to search, skipping any labels, jumps
448 and notes at the beginning and end of the block. Then count the total
449 number of insns and see if it is small enough to convert. */
450 then_start
= first_active_insn (then_bb
);
451 then_end
= last_active_insn (then_bb
, TRUE
);
452 n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
453 max
= MAX_CONDITIONAL_EXECUTE
;
458 else_start
= first_active_insn (else_bb
);
459 else_end
= last_active_insn (else_bb
, TRUE
);
460 n_insns
+= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
466 /* Map test_expr/test_jump into the appropriate MD tests to use on
467 the conditionally executed code. */
469 true_expr
= test_expr
;
471 false_code
= reversed_comparison_code (true_expr
, BB_END (test_bb
));
472 if (false_code
!= UNKNOWN
)
473 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
474 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
476 false_expr
= NULL_RTX
;
478 #ifdef IFCVT_MODIFY_TESTS
479 /* If the machine description needs to modify the tests, such as setting a
480 conditional execution register from a comparison, it can do so here. */
481 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
483 /* See if the conversion failed. */
484 if (!true_expr
|| !false_expr
)
488 true_prob_val
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
491 true_prob_val
= XEXP (true_prob_val
, 0);
492 false_prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (true_prob_val
));
495 false_prob_val
= NULL_RTX
;
497 /* If we have && or || tests, do them here. These tests are in the adjacent
498 blocks after the first block containing the test. */
499 if (ce_info
->num_multiple_test_blocks
> 0)
501 basic_block bb
= test_bb
;
502 basic_block last_test_bb
= ce_info
->last_test_bb
;
511 enum rtx_code f_code
;
513 bb
= block_fallthru (bb
);
514 start
= first_active_insn (bb
);
515 end
= last_active_insn (bb
, TRUE
);
517 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
518 false_prob_val
, FALSE
))
521 /* If the conditional jump is more than just a conditional jump, then
522 we can not do conditional execution conversion on this block. */
523 if (! onlyjump_p (BB_END (bb
)))
526 /* Find the conditional jump and isolate the test. */
527 t
= cond_exec_get_condition (BB_END (bb
));
531 f_code
= reversed_comparison_code (t
, BB_END (bb
));
532 if (f_code
== UNKNOWN
)
535 f
= gen_rtx_fmt_ee (f_code
, GET_MODE (t
), XEXP (t
, 0), XEXP (t
, 1));
536 if (ce_info
->and_and_p
)
538 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
539 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
543 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
544 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
547 /* If the machine description needs to modify the tests, such as
548 setting a conditional execution register from a comparison, it can
550 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
551 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
553 /* See if the conversion failed. */
561 while (bb
!= last_test_bb
);
564 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
565 on then THEN block. */
566 then_mod_ok
= (else_bb
== NULL_BLOCK
);
568 /* Go through the THEN and ELSE blocks converting the insns if possible
569 to conditional execution. */
573 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
574 false_expr
, false_prob_val
,
578 if (else_bb
&& else_end
579 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
580 true_expr
, true_prob_val
, TRUE
))
583 /* If we cannot apply the changes, fail. Do not go through the normal fail
584 processing, since apply_change_group will call cancel_changes. */
585 if (! apply_change_group ())
587 #ifdef IFCVT_MODIFY_CANCEL
588 /* Cancel any machine dependent changes. */
589 IFCVT_MODIFY_CANCEL (ce_info
);
594 #ifdef IFCVT_MODIFY_FINAL
595 /* Do any machine dependent final modifications. */
596 IFCVT_MODIFY_FINAL (ce_info
);
599 /* Conversion succeeded. */
601 fprintf (dump_file
, "%d insn%s converted to conditional execution.\n",
602 n_insns
, (n_insns
== 1) ? " was" : "s were");
604 /* Merge the blocks! */
605 merge_if_block (ce_info
);
606 cond_exec_changed_p
= TRUE
;
610 #ifdef IFCVT_MODIFY_CANCEL
611 /* Cancel any machine dependent changes. */
612 IFCVT_MODIFY_CANCEL (ce_info
);
619 /* Used by noce_process_if_block to communicate with its subroutines.
621 The subroutines know that A and B may be evaluated freely. They
622 know that X is a register. They should insert new instructions
623 before cond_earliest. */
630 rtx jump
, cond
, cond_earliest
;
631 /* True if "b" was originally evaluated unconditionally. */
632 bool b_unconditional
;
635 static rtx
noce_emit_store_flag (struct noce_if_info
*, rtx
, int, int);
636 static int noce_try_move (struct noce_if_info
*);
637 static int noce_try_store_flag (struct noce_if_info
*);
638 static int noce_try_addcc (struct noce_if_info
*);
639 static int noce_try_store_flag_constants (struct noce_if_info
*);
640 static int noce_try_store_flag_mask (struct noce_if_info
*);
641 static rtx
noce_emit_cmove (struct noce_if_info
*, rtx
, enum rtx_code
, rtx
,
643 static int noce_try_cmove (struct noce_if_info
*);
644 static int noce_try_cmove_arith (struct noce_if_info
*);
645 static rtx
noce_get_alt_condition (struct noce_if_info
*, rtx
, rtx
*);
646 static int noce_try_minmax (struct noce_if_info
*);
647 static int noce_try_abs (struct noce_if_info
*);
648 static int noce_try_sign_mask (struct noce_if_info
*);
650 /* Helper function for noce_try_store_flag*. */
653 noce_emit_store_flag (struct noce_if_info
*if_info
, rtx x
, int reversep
,
656 rtx cond
= if_info
->cond
;
660 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
661 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
663 /* If earliest == jump, or when the condition is complex, try to
664 build the store_flag insn directly. */
667 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
670 code
= reversed_comparison_code (cond
, if_info
->jump
);
672 code
= GET_CODE (cond
);
674 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
675 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
679 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
681 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
684 tmp
= emit_insn (tmp
);
686 if (recog_memoized (tmp
) >= 0)
692 if_info
->cond_earliest
= if_info
->jump
;
700 /* Don't even try if the comparison operands or the mode of X are weird. */
701 if (cond_complex
|| !SCALAR_INT_MODE_P (GET_MODE (x
)))
704 return emit_store_flag (x
, code
, XEXP (cond
, 0),
705 XEXP (cond
, 1), VOIDmode
,
706 (code
== LTU
|| code
== LEU
707 || code
== GEU
|| code
== GTU
), normalize
);
710 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
711 X is the destination/target and Y is the value to copy. */
714 noce_emit_move_insn (rtx x
, rtx y
)
716 enum machine_mode outmode
, inmode
;
720 if (GET_CODE (x
) != STRICT_LOW_PART
)
722 emit_move_insn (x
, y
);
727 inner
= XEXP (outer
, 0);
728 outmode
= GET_MODE (outer
);
729 inmode
= GET_MODE (inner
);
730 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
731 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
);
734 /* Return sequence of instructions generated by if conversion. This
735 function calls end_sequence() to end the current stream, ensures
736 that are instructions are unshared, recognizable non-jump insns.
737 On failure, this function returns a NULL_RTX. */
740 end_ifcvt_sequence (struct noce_if_info
*if_info
)
743 rtx seq
= get_insns ();
745 set_used_flags (if_info
->x
);
746 set_used_flags (if_info
->cond
);
747 unshare_all_rtl_in_chain (seq
);
750 /* Make sure that all of the instructions emitted are recognizable,
751 and that we haven't introduced a new jump instruction.
752 As an exercise for the reader, build a general mechanism that
753 allows proper placement of required clobbers. */
754 for (insn
= seq
; insn
; insn
= NEXT_INSN (insn
))
756 || recog_memoized (insn
) == -1)
762 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
763 "if (a == b) x = a; else x = b" into "x = b". */
766 noce_try_move (struct noce_if_info
*if_info
)
768 rtx cond
= if_info
->cond
;
769 enum rtx_code code
= GET_CODE (cond
);
772 if (code
!= NE
&& code
!= EQ
)
775 /* This optimization isn't valid if either A or B could be a NaN
777 if (HONOR_NANS (GET_MODE (if_info
->x
))
778 || HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
781 /* Check whether the operands of the comparison are A and in
783 if ((rtx_equal_p (if_info
->a
, XEXP (cond
, 0))
784 && rtx_equal_p (if_info
->b
, XEXP (cond
, 1)))
785 || (rtx_equal_p (if_info
->a
, XEXP (cond
, 1))
786 && rtx_equal_p (if_info
->b
, XEXP (cond
, 0))))
788 y
= (code
== EQ
) ? if_info
->a
: if_info
->b
;
790 /* Avoid generating the move if the source is the destination. */
791 if (! rtx_equal_p (if_info
->x
, y
))
794 noce_emit_move_insn (if_info
->x
, y
);
795 seq
= end_ifcvt_sequence (if_info
);
799 emit_insn_before_setloc (seq
, if_info
->jump
,
800 INSN_LOCATOR (if_info
->insn_a
));
807 /* Convert "if (test) x = 1; else x = 0".
809 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
810 tried in noce_try_store_flag_constants after noce_try_cmove has had
811 a go at the conversion. */
814 noce_try_store_flag (struct noce_if_info
*if_info
)
819 if (GET_CODE (if_info
->b
) == CONST_INT
820 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
821 && if_info
->a
== const0_rtx
)
823 else if (if_info
->b
== const0_rtx
824 && GET_CODE (if_info
->a
) == CONST_INT
825 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
826 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
834 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
837 if (target
!= if_info
->x
)
838 noce_emit_move_insn (if_info
->x
, target
);
840 seq
= end_ifcvt_sequence (if_info
);
844 emit_insn_before_setloc (seq
, if_info
->jump
,
845 INSN_LOCATOR (if_info
->insn_a
));
855 /* Convert "if (test) x = a; else x = b", for A and B constant. */
858 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
862 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
863 int normalize
, can_reverse
;
864 enum machine_mode mode
;
867 && GET_CODE (if_info
->a
) == CONST_INT
868 && GET_CODE (if_info
->b
) == CONST_INT
)
870 mode
= GET_MODE (if_info
->x
);
871 ifalse
= INTVAL (if_info
->a
);
872 itrue
= INTVAL (if_info
->b
);
874 /* Make sure we can represent the difference between the two values. */
875 if ((itrue
- ifalse
> 0)
876 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
879 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
881 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
885 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
887 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
888 && (STORE_FLAG_VALUE
== 1
889 || BRANCH_COST
>= 2))
891 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
892 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
893 normalize
= 1, reversep
= 1;
895 && (STORE_FLAG_VALUE
== -1
896 || BRANCH_COST
>= 2))
898 else if (ifalse
== -1 && can_reverse
899 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
900 normalize
= -1, reversep
= 1;
901 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
909 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
910 diff
= trunc_int_for_mode (-diff
, mode
);
914 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
921 /* if (test) x = 3; else x = 4;
922 => x = 3 + (test == 0); */
923 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
925 target
= expand_simple_binop (mode
,
926 (diff
== STORE_FLAG_VALUE
928 GEN_INT (ifalse
), target
, if_info
->x
, 0,
932 /* if (test) x = 8; else x = 0;
933 => x = (test != 0) << 3; */
934 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
936 target
= expand_simple_binop (mode
, ASHIFT
,
937 target
, GEN_INT (tmp
), if_info
->x
, 0,
941 /* if (test) x = -1; else x = b;
942 => x = -(test != 0) | b; */
943 else if (itrue
== -1)
945 target
= expand_simple_binop (mode
, IOR
,
946 target
, GEN_INT (ifalse
), if_info
->x
, 0,
950 /* if (test) x = a; else x = b;
951 => x = (-(test != 0) & (b - a)) + a; */
954 target
= expand_simple_binop (mode
, AND
,
955 target
, GEN_INT (diff
), if_info
->x
, 0,
958 target
= expand_simple_binop (mode
, PLUS
,
959 target
, GEN_INT (ifalse
),
960 if_info
->x
, 0, OPTAB_WIDEN
);
969 if (target
!= if_info
->x
)
970 noce_emit_move_insn (if_info
->x
, target
);
972 seq
= end_ifcvt_sequence (if_info
);
976 emit_insn_before_setloc (seq
, if_info
->jump
,
977 INSN_LOCATOR (if_info
->insn_a
));
984 /* Convert "if (test) foo++" into "foo += (test != 0)", and
985 similarly for "foo--". */
988 noce_try_addcc (struct noce_if_info
*if_info
)
991 int subtract
, normalize
;
994 && GET_CODE (if_info
->a
) == PLUS
995 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
996 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
999 rtx cond
= if_info
->cond
;
1000 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
1002 /* First try to use addcc pattern. */
1003 if (general_operand (XEXP (cond
, 0), VOIDmode
)
1004 && general_operand (XEXP (cond
, 1), VOIDmode
))
1007 target
= emit_conditional_add (if_info
->x
, code
,
1012 XEXP (if_info
->a
, 1),
1013 GET_MODE (if_info
->x
),
1014 (code
== LTU
|| code
== GEU
1015 || code
== LEU
|| code
== GTU
));
1018 if (target
!= if_info
->x
)
1019 noce_emit_move_insn (if_info
->x
, target
);
1021 seq
= end_ifcvt_sequence (if_info
);
1025 emit_insn_before_setloc (seq
, if_info
->jump
,
1026 INSN_LOCATOR (if_info
->insn_a
));
1032 /* If that fails, construct conditional increment or decrement using
1034 if (BRANCH_COST
>= 2
1035 && (XEXP (if_info
->a
, 1) == const1_rtx
1036 || XEXP (if_info
->a
, 1) == constm1_rtx
))
1039 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1040 subtract
= 0, normalize
= 0;
1041 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1042 subtract
= 1, normalize
= 0;
1044 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
1047 target
= noce_emit_store_flag (if_info
,
1048 gen_reg_rtx (GET_MODE (if_info
->x
)),
1052 target
= expand_simple_binop (GET_MODE (if_info
->x
),
1053 subtract
? MINUS
: PLUS
,
1054 if_info
->b
, target
, if_info
->x
,
1058 if (target
!= if_info
->x
)
1059 noce_emit_move_insn (if_info
->x
, target
);
1061 seq
= end_ifcvt_sequence (if_info
);
1065 emit_insn_before_setloc (seq
, if_info
->jump
,
1066 INSN_LOCATOR (if_info
->insn_a
));
1076 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1079 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
1085 if (! no_new_pseudos
1086 && (BRANCH_COST
>= 2
1087 || STORE_FLAG_VALUE
== -1)
1088 && ((if_info
->a
== const0_rtx
1089 && rtx_equal_p (if_info
->b
, if_info
->x
))
1090 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
1093 && if_info
->b
== const0_rtx
1094 && rtx_equal_p (if_info
->a
, if_info
->x
))))
1097 target
= noce_emit_store_flag (if_info
,
1098 gen_reg_rtx (GET_MODE (if_info
->x
)),
1101 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
1103 target
, if_info
->x
, 0,
1108 if (target
!= if_info
->x
)
1109 noce_emit_move_insn (if_info
->x
, target
);
1111 seq
= end_ifcvt_sequence (if_info
);
1115 emit_insn_before_setloc (seq
, if_info
->jump
,
1116 INSN_LOCATOR (if_info
->insn_a
));
1126 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1129 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1130 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1132 /* If earliest == jump, try to build the cmove insn directly.
1133 This is helpful when combine has created some complex condition
1134 (like for alpha's cmovlbs) that we can't hope to regenerate
1135 through the normal interface. */
1137 if (if_info
->cond_earliest
== if_info
->jump
)
1141 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1142 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1143 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1146 tmp
= emit_insn (tmp
);
1148 if (recog_memoized (tmp
) >= 0)
1160 /* Don't even try if the comparison operands are weird. */
1161 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1162 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1165 #if HAVE_conditional_move
1166 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1167 vtrue
, vfalse
, GET_MODE (x
),
1168 (code
== LTU
|| code
== GEU
1169 || code
== LEU
|| code
== GTU
));
1171 /* We'll never get here, as noce_process_if_block doesn't call the
1172 functions involved. Ifdef code, however, should be discouraged
1173 because it leads to typos in the code not selected. However,
1174 emit_conditional_move won't exist either. */
1179 /* Try only simple constants and registers here. More complex cases
1180 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1181 has had a go at it. */
1184 noce_try_cmove (struct noce_if_info
*if_info
)
1189 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1190 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1194 code
= GET_CODE (if_info
->cond
);
1195 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1196 XEXP (if_info
->cond
, 0),
1197 XEXP (if_info
->cond
, 1),
1198 if_info
->a
, if_info
->b
);
1202 if (target
!= if_info
->x
)
1203 noce_emit_move_insn (if_info
->x
, target
);
1205 seq
= end_ifcvt_sequence (if_info
);
1209 emit_insn_before_setloc (seq
, if_info
->jump
,
1210 INSN_LOCATOR (if_info
->insn_a
));
1223 /* Try more complex cases involving conditional_move. */
1226 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1237 /* A conditional move from two memory sources is equivalent to a
1238 conditional on their addresses followed by a load. Don't do this
1239 early because it'll screw alias analysis. Note that we've
1240 already checked for no side effects. */
1241 if (! no_new_pseudos
&& cse_not_expected
1242 && MEM_P (a
) && MEM_P (b
)
1243 && BRANCH_COST
>= 5)
1247 x
= gen_reg_rtx (Pmode
);
1251 /* ??? We could handle this if we knew that a load from A or B could
1252 not fault. This is also true if we've already loaded
1253 from the address along the path from ENTRY. */
1254 else if (may_trap_p (a
) || may_trap_p (b
))
1257 /* if (test) x = a + b; else x = c - d;
1264 code
= GET_CODE (if_info
->cond
);
1265 insn_a
= if_info
->insn_a
;
1266 insn_b
= if_info
->insn_b
;
1268 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1269 if insn_rtx_cost can't be estimated. */
1272 insn_cost
= insn_rtx_cost (PATTERN (insn_a
));
1273 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1282 insn_cost
+= insn_rtx_cost (PATTERN (insn_b
));
1283 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1287 /* Possibly rearrange operands to make things come out more natural. */
1288 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1291 if (rtx_equal_p (b
, x
))
1293 else if (general_operand (b
, GET_MODE (b
)))
1298 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1299 tmp
= a
, a
= b
, b
= tmp
;
1300 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1306 /* If either operand is complex, load it into a register first.
1307 The best way to do this is to copy the original insn. In this
1308 way we preserve any clobbers etc that the insn may have had.
1309 This is of course not possible in the IS_MEM case. */
1310 if (! general_operand (a
, GET_MODE (a
)))
1315 goto end_seq_and_fail
;
1319 tmp
= gen_reg_rtx (GET_MODE (a
));
1320 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1323 goto end_seq_and_fail
;
1326 a
= gen_reg_rtx (GET_MODE (a
));
1327 tmp
= copy_rtx (insn_a
);
1328 set
= single_set (tmp
);
1330 tmp
= emit_insn (PATTERN (tmp
));
1332 if (recog_memoized (tmp
) < 0)
1333 goto end_seq_and_fail
;
1335 if (! general_operand (b
, GET_MODE (b
)))
1340 goto end_seq_and_fail
;
1344 tmp
= gen_reg_rtx (GET_MODE (b
));
1345 tmp
= emit_insn (gen_rtx_SET (VOIDmode
,
1350 goto end_seq_and_fail
;
1353 b
= gen_reg_rtx (GET_MODE (b
));
1354 tmp
= copy_rtx (insn_b
);
1355 set
= single_set (tmp
);
1357 tmp
= emit_insn (PATTERN (tmp
));
1359 if (recog_memoized (tmp
) < 0)
1360 goto end_seq_and_fail
;
1363 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1364 XEXP (if_info
->cond
, 1), a
, b
);
1367 goto end_seq_and_fail
;
1369 /* If we're handling a memory for above, emit the load now. */
1372 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1374 /* Copy over flags as appropriate. */
1375 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1376 MEM_VOLATILE_P (tmp
) = 1;
1377 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1378 MEM_IN_STRUCT_P (tmp
) = 1;
1379 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1380 MEM_SCALAR_P (tmp
) = 1;
1381 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1382 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1384 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1386 noce_emit_move_insn (if_info
->x
, tmp
);
1388 else if (target
!= x
)
1389 noce_emit_move_insn (x
, target
);
1391 tmp
= end_ifcvt_sequence (if_info
);
1395 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1403 /* For most cases, the simplified condition we found is the best
1404 choice, but this is not the case for the min/max/abs transforms.
1405 For these we wish to know that it is A or B in the condition. */
1408 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1411 rtx cond
, set
, insn
;
1414 /* If target is already mentioned in the known condition, return it. */
1415 if (reg_mentioned_p (target
, if_info
->cond
))
1417 *earliest
= if_info
->cond_earliest
;
1418 return if_info
->cond
;
1421 set
= pc_set (if_info
->jump
);
1422 cond
= XEXP (SET_SRC (set
), 0);
1424 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1425 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1427 /* If we're looking for a constant, try to make the conditional
1428 have that constant in it. There are two reasons why it may
1429 not have the constant we want:
1431 1. GCC may have needed to put the constant in a register, because
1432 the target can't compare directly against that constant. For
1433 this case, we look for a SET immediately before the comparison
1434 that puts a constant in that register.
1436 2. GCC may have canonicalized the conditional, for example
1437 replacing "if x < 4" with "if x <= 3". We can undo that (or
1438 make equivalent types of changes) to get the constants we need
1439 if they're off by one in the right direction. */
1441 if (GET_CODE (target
) == CONST_INT
)
1443 enum rtx_code code
= GET_CODE (if_info
->cond
);
1444 rtx op_a
= XEXP (if_info
->cond
, 0);
1445 rtx op_b
= XEXP (if_info
->cond
, 1);
1448 /* First, look to see if we put a constant in a register. */
1449 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1451 && INSN_P (prev_insn
)
1452 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1454 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1456 src
= SET_SRC (PATTERN (prev_insn
));
1457 if (GET_CODE (src
) == CONST_INT
)
1459 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1461 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1464 if (GET_CODE (op_a
) == CONST_INT
)
1469 code
= swap_condition (code
);
1474 /* Now, look to see if we can get the right constant by
1475 adjusting the conditional. */
1476 if (GET_CODE (op_b
) == CONST_INT
)
1478 HOST_WIDE_INT desired_val
= INTVAL (target
);
1479 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1484 if (actual_val
== desired_val
+ 1)
1487 op_b
= GEN_INT (desired_val
);
1491 if (actual_val
== desired_val
- 1)
1494 op_b
= GEN_INT (desired_val
);
1498 if (actual_val
== desired_val
- 1)
1501 op_b
= GEN_INT (desired_val
);
1505 if (actual_val
== desired_val
+ 1)
1508 op_b
= GEN_INT (desired_val
);
1516 /* If we made any changes, generate a new conditional that is
1517 equivalent to what we started with, but has the right
1519 if (code
!= GET_CODE (if_info
->cond
)
1520 || op_a
!= XEXP (if_info
->cond
, 0)
1521 || op_b
!= XEXP (if_info
->cond
, 1))
1523 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1524 *earliest
= if_info
->cond_earliest
;
1529 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1530 earliest
, target
, false, true);
1531 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1534 /* We almost certainly searched back to a different place.
1535 Need to re-verify correct lifetimes. */
1537 /* X may not be mentioned in the range (cond_earliest, jump]. */
1538 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1539 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1542 /* A and B may not be modified in the range [cond_earliest, jump). */
1543 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1545 && (modified_in_p (if_info
->a
, insn
)
1546 || modified_in_p (if_info
->b
, insn
)))
1552 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1555 noce_try_minmax (struct noce_if_info
*if_info
)
1557 rtx cond
, earliest
, target
, seq
;
1558 enum rtx_code code
, op
;
1561 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1565 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1566 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1567 to get the target to tell us... */
1568 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1569 || HONOR_NANS (GET_MODE (if_info
->x
)))
1572 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1576 /* Verify the condition is of the form we expect, and canonicalize
1577 the comparison code. */
1578 code
= GET_CODE (cond
);
1579 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1581 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1584 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1586 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1588 code
= swap_condition (code
);
1593 /* Determine what sort of operation this is. Note that the code is for
1594 a taken branch, so the code->operation mapping appears backwards. */
1627 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1628 if_info
->a
, if_info
->b
,
1629 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1635 if (target
!= if_info
->x
)
1636 noce_emit_move_insn (if_info
->x
, target
);
1638 seq
= end_ifcvt_sequence (if_info
);
1642 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1643 if_info
->cond
= cond
;
1644 if_info
->cond_earliest
= earliest
;
1649 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1652 noce_try_abs (struct noce_if_info
*if_info
)
1654 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1657 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1661 /* Recognize A and B as constituting an ABS or NABS. */
1664 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1666 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1668 c
= a
; a
= b
; b
= c
;
1674 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1678 /* Verify the condition is of the form we expect. */
1679 if (rtx_equal_p (XEXP (cond
, 0), b
))
1681 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1686 /* Verify that C is zero. Search backward through the block for
1687 a REG_EQUAL note if necessary. */
1690 rtx insn
, note
= NULL
;
1691 for (insn
= earliest
;
1692 insn
!= BB_HEAD (if_info
->test_bb
);
1693 insn
= PREV_INSN (insn
))
1695 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1696 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1703 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1704 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1705 c
= get_pool_constant (XEXP (c
, 0));
1707 /* Work around funny ideas get_condition has wrt canonicalization.
1708 Note that these rtx constants are known to be CONST_INT, and
1709 therefore imply integer comparisons. */
1710 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1712 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1714 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1717 /* Determine what sort of operation this is. */
1718 switch (GET_CODE (cond
))
1737 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1739 /* ??? It's a quandary whether cmove would be better here, especially
1740 for integers. Perhaps combine will clean things up. */
1741 if (target
&& negate
)
1742 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1750 if (target
!= if_info
->x
)
1751 noce_emit_move_insn (if_info
->x
, target
);
1753 seq
= end_ifcvt_sequence (if_info
);
1757 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1758 if_info
->cond
= cond
;
1759 if_info
->cond_earliest
= earliest
;
1764 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1767 noce_try_sign_mask (struct noce_if_info
*if_info
)
1769 rtx cond
, t
, m
, c
, seq
;
1770 enum machine_mode mode
;
1776 cond
= if_info
->cond
;
1777 code
= GET_CODE (cond
);
1782 if (if_info
->a
== const0_rtx
)
1784 if ((code
== LT
&& c
== const0_rtx
)
1785 || (code
== LE
&& c
== constm1_rtx
))
1788 else if (if_info
->b
== const0_rtx
)
1790 if ((code
== GE
&& c
== const0_rtx
)
1791 || (code
== GT
&& c
== constm1_rtx
))
1795 if (! t
|| side_effects_p (t
))
1798 /* We currently don't handle different modes. */
1799 mode
= GET_MODE (t
);
1800 if (GET_MODE (m
) != mode
)
1803 /* This is only profitable if T is cheap, or T is unconditionally
1804 executed/evaluated in the original insn sequence. */
1805 if (rtx_cost (t
, SET
) >= COSTS_N_INSNS (2)
1806 && (!if_info
->b_unconditional
1807 || t
!= if_info
->b
))
1811 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1812 "(signed) m >> 31" directly. This benefits targets with specialized
1813 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1814 m
= emit_store_flag (gen_reg_rtx (mode
), LT
, m
, const0_rtx
, mode
, 0, -1);
1815 t
= m
? expand_binop (mode
, and_optab
, m
, t
, NULL_RTX
, 0, OPTAB_DIRECT
)
1824 noce_emit_move_insn (if_info
->x
, t
);
1826 seq
= end_ifcvt_sequence (if_info
);
1830 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1835 /* Similar to get_condition, only the resulting condition must be
1836 valid at JUMP, instead of at EARLIEST. */
1839 noce_get_condition (rtx jump
, rtx
*earliest
)
1844 if (! any_condjump_p (jump
))
1847 set
= pc_set (jump
);
1849 /* If this branches to JUMP_LABEL when the condition is false,
1850 reverse the condition. */
1851 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1852 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1854 /* If the condition variable is a register and is MODE_INT, accept it. */
1856 cond
= XEXP (SET_SRC (set
), 0);
1857 tmp
= XEXP (cond
, 0);
1858 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1863 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1864 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1868 /* Otherwise, fall back on canonicalize_condition to do the dirty
1869 work of manipulating MODE_CC values and COMPARE rtx codes. */
1870 return canonicalize_condition (jump
, cond
, reverse
, earliest
,
1871 NULL_RTX
, false, true);
1874 /* Return true if OP is ok for if-then-else processing. */
1877 noce_operand_ok (rtx op
)
1879 /* We special-case memories, so handle any of them with
1880 no address side effects. */
1882 return ! side_effects_p (XEXP (op
, 0));
1884 if (side_effects_p (op
))
1887 return ! may_trap_p (op
);
1890 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1891 without using conditional execution. Return TRUE if we were
1892 successful at converting the block. */
1895 noce_process_if_block (struct ce_if_block
* ce_info
)
1897 basic_block test_bb
= ce_info
->test_bb
; /* test block */
1898 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1899 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1900 struct noce_if_info if_info
;
1903 rtx orig_x
, x
, a
, b
;
1906 /* We're looking for patterns of the form
1908 (1) if (...) x = a; else x = b;
1909 (2) x = b; if (...) x = a;
1910 (3) if (...) x = a; // as if with an initial x = x.
1912 The later patterns require jumps to be more expensive.
1914 ??? For future expansion, look for multiple X in such patterns. */
1916 /* If test is comprised of && or || elements, don't handle it unless it is
1917 the special case of && elements without an ELSE block. */
1918 if (ce_info
->num_multiple_test_blocks
)
1920 if (else_bb
|| ! ce_info
->and_and_p
)
1923 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
1924 ce_info
->num_multiple_test_blocks
= 0;
1925 ce_info
->num_and_and_blocks
= 0;
1926 ce_info
->num_or_or_blocks
= 0;
1929 /* If this is not a standard conditional jump, we can't parse it. */
1930 jump
= BB_END (test_bb
);
1931 cond
= noce_get_condition (jump
, &if_info
.cond_earliest
);
1935 /* If the conditional jump is more than just a conditional
1936 jump, then we can not do if-conversion on this block. */
1937 if (! onlyjump_p (jump
))
1940 /* We must be comparing objects whose modes imply the size. */
1941 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
1944 /* Look for one of the potential sets. */
1945 insn_a
= first_active_insn (then_bb
);
1947 || insn_a
!= last_active_insn (then_bb
, FALSE
)
1948 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
1951 x
= SET_DEST (set_a
);
1952 a
= SET_SRC (set_a
);
1954 /* Look for the other potential set. Make sure we've got equivalent
1956 /* ??? This is overconservative. Storing to two different mems is
1957 as easy as conditionally computing the address. Storing to a
1958 single mem merely requires a scratch memory to use as one of the
1959 destination addresses; often the memory immediately below the
1960 stack pointer is available for this. */
1964 insn_b
= first_active_insn (else_bb
);
1966 || insn_b
!= last_active_insn (else_bb
, FALSE
)
1967 || (set_b
= single_set (insn_b
)) == NULL_RTX
1968 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
1973 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
1974 /* We're going to be moving the evaluation of B down from above
1975 COND_EARLIEST to JUMP. Make sure the relevant data is still
1978 || !NONJUMP_INSN_P (insn_b
)
1979 || (set_b
= single_set (insn_b
)) == NULL_RTX
1980 || ! rtx_equal_p (x
, SET_DEST (set_b
))
1981 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
1982 || modified_between_p (SET_SRC (set_b
),
1983 PREV_INSN (if_info
.cond_earliest
), jump
)
1984 /* Likewise with X. In particular this can happen when
1985 noce_get_condition looks farther back in the instruction
1986 stream than one might expect. */
1987 || reg_overlap_mentioned_p (x
, cond
)
1988 || reg_overlap_mentioned_p (x
, a
)
1989 || modified_between_p (x
, PREV_INSN (if_info
.cond_earliest
), jump
))
1990 insn_b
= set_b
= NULL_RTX
;
1993 /* If x has side effects then only the if-then-else form is safe to
1994 convert. But even in that case we would need to restore any notes
1995 (such as REG_INC) at then end. That can be tricky if
1996 noce_emit_move_insn expands to more than one insn, so disable the
1997 optimization entirely for now if there are side effects. */
1998 if (side_effects_p (x
))
2001 b
= (set_b
? SET_SRC (set_b
) : x
);
2003 /* Only operate on register destinations, and even then avoid extending
2004 the lifetime of hard registers on small register class machines. */
2007 || (SMALL_REGISTER_CLASSES
2008 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
2010 if (no_new_pseudos
|| GET_MODE (x
) == BLKmode
)
2012 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
2013 ? XEXP (x
, 0) : x
));
2016 /* Don't operate on sources that may trap or are volatile. */
2017 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
2020 /* Set up the info block for our subroutines. */
2021 if_info
.test_bb
= test_bb
;
2022 if_info
.cond
= cond
;
2023 if_info
.jump
= jump
;
2024 if_info
.insn_a
= insn_a
;
2025 if_info
.insn_b
= insn_b
;
2029 if_info
.b_unconditional
= else_bb
== 0;
2031 /* Try optimizations in some approximation of a useful order. */
2032 /* ??? Should first look to see if X is live incoming at all. If it
2033 isn't, we don't need anything but an unconditional set. */
2035 /* Look and see if A and B are really the same. Avoid creating silly
2036 cmove constructs that no one will fix up later. */
2037 if (rtx_equal_p (a
, b
))
2039 /* If we have an INSN_B, we don't have to create any new rtl. Just
2040 move the instruction that we already have. If we don't have an
2041 INSN_B, that means that A == X, and we've got a noop move. In
2042 that case don't do anything and let the code below delete INSN_A. */
2043 if (insn_b
&& else_bb
)
2047 if (else_bb
&& insn_b
== BB_END (else_bb
))
2048 BB_END (else_bb
) = PREV_INSN (insn_b
);
2049 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
2051 /* If there was a REG_EQUAL note, delete it since it may have been
2052 true due to this insn being after a jump. */
2053 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
2054 remove_note (insn_b
, note
);
2058 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2059 x must be executed twice. */
2060 else if (insn_b
&& side_effects_p (orig_x
))
2067 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2068 for most optimizations if writing to x may trap, i.e. it's a memory
2069 other than a static var or a stack slot. */
2072 && ! MEM_NOTRAP_P (orig_x
)
2073 && rtx_addr_can_trap_p (XEXP (orig_x
, 0)))
2075 if (HAVE_conditional_move
)
2077 if (noce_try_cmove (&if_info
))
2079 if (! HAVE_conditional_execution
2080 && noce_try_cmove_arith (&if_info
))
2086 if (noce_try_move (&if_info
))
2088 if (noce_try_store_flag (&if_info
))
2090 if (noce_try_minmax (&if_info
))
2092 if (noce_try_abs (&if_info
))
2094 if (HAVE_conditional_move
2095 && noce_try_cmove (&if_info
))
2097 if (! HAVE_conditional_execution
)
2099 if (noce_try_store_flag_constants (&if_info
))
2101 if (noce_try_addcc (&if_info
))
2103 if (noce_try_store_flag_mask (&if_info
))
2105 if (HAVE_conditional_move
2106 && noce_try_cmove_arith (&if_info
))
2108 if (noce_try_sign_mask (&if_info
))
2115 /* The original sets may now be killed. */
2116 delete_insn (insn_a
);
2118 /* Several special cases here: First, we may have reused insn_b above,
2119 in which case insn_b is now NULL. Second, we want to delete insn_b
2120 if it came from the ELSE block, because follows the now correct
2121 write that appears in the TEST block. However, if we got insn_b from
2122 the TEST block, it may in fact be loading data needed for the comparison.
2123 We'll let life_analysis remove the insn if it's really dead. */
2124 if (insn_b
&& else_bb
)
2125 delete_insn (insn_b
);
2127 /* The new insns will have been inserted immediately before the jump. We
2128 should be able to remove the jump with impunity, but the condition itself
2129 may have been modified by gcse to be shared across basic blocks. */
2132 /* If we used a temporary, fix it up now. */
2136 noce_emit_move_insn (orig_x
, x
);
2137 insn_b
= get_insns ();
2138 set_used_flags (orig_x
);
2139 unshare_all_rtl_in_chain (insn_b
);
2142 emit_insn_after_setloc (insn_b
, BB_END (test_bb
), INSN_LOCATOR (insn_a
));
2145 /* Merge the blocks! */
2146 merge_if_block (ce_info
);
2151 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2152 straight line code. Return true if successful. */
2155 process_if_block (struct ce_if_block
* ce_info
)
2157 if (! reload_completed
2158 && noce_process_if_block (ce_info
))
2161 if (HAVE_conditional_execution
&& reload_completed
)
2163 /* If we have && and || tests, try to first handle combining the && and
2164 || tests into the conditional code, and if that fails, go back and
2165 handle it without the && and ||, which at present handles the && case
2166 if there was no ELSE block. */
2167 if (cond_exec_process_if_block (ce_info
, TRUE
))
2170 if (ce_info
->num_multiple_test_blocks
)
2174 if (cond_exec_process_if_block (ce_info
, FALSE
))
2182 /* Merge the blocks and mark for local life update. */
2185 merge_if_block (struct ce_if_block
* ce_info
)
2187 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
2188 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
2189 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
2190 basic_block join_bb
= ce_info
->join_bb
; /* join block */
2191 basic_block combo_bb
;
2193 /* All block merging is done into the lower block numbers. */
2197 /* Merge any basic blocks to handle && and || subtests. Each of
2198 the blocks are on the fallthru path from the predecessor block. */
2199 if (ce_info
->num_multiple_test_blocks
> 0)
2201 basic_block bb
= test_bb
;
2202 basic_block last_test_bb
= ce_info
->last_test_bb
;
2203 basic_block fallthru
= block_fallthru (bb
);
2208 fallthru
= block_fallthru (bb
);
2209 merge_blocks (combo_bb
, bb
);
2212 while (bb
!= last_test_bb
);
2215 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2216 label, but it might if there were || tests. That label's count should be
2217 zero, and it normally should be removed. */
2221 if (combo_bb
->global_live_at_end
)
2222 COPY_REG_SET (combo_bb
->global_live_at_end
,
2223 then_bb
->global_live_at_end
);
2224 merge_blocks (combo_bb
, then_bb
);
2228 /* The ELSE block, if it existed, had a label. That label count
2229 will almost always be zero, but odd things can happen when labels
2230 get their addresses taken. */
2233 merge_blocks (combo_bb
, else_bb
);
2237 /* If there was no join block reported, that means it was not adjacent
2238 to the others, and so we cannot merge them. */
2242 rtx last
= BB_END (combo_bb
);
2244 /* The outgoing edge for the current COMBO block should already
2245 be correct. Verify this. */
2246 if (EDGE_COUNT (combo_bb
->succs
) == 0)
2248 if (find_reg_note (last
, REG_NORETURN
, NULL
))
2250 else if (NONJUMP_INSN_P (last
)
2251 && GET_CODE (PATTERN (last
)) == TRAP_IF
2252 && TRAP_CONDITION (PATTERN (last
)) == const_true_rtx
)
2258 /* There should still be something at the end of the THEN or ELSE
2259 blocks taking us to our final destination. */
2260 else if (JUMP_P (last
))
2262 else if (EDGE_SUCC (combo_bb
, 0)->dest
== EXIT_BLOCK_PTR
2264 && SIBLING_CALL_P (last
))
2266 else if ((EDGE_SUCC (combo_bb
, 0)->flags
& EDGE_EH
)
2267 && can_throw_internal (last
))
2273 /* The JOIN block may have had quite a number of other predecessors too.
2274 Since we've already merged the TEST, THEN and ELSE blocks, we should
2275 have only one remaining edge from our if-then-else diamond. If there
2276 is more than one remaining edge, it must come from elsewhere. There
2277 may be zero incoming edges if the THEN block didn't actually join
2278 back up (as with a call to abort). */
2279 else if (EDGE_COUNT (join_bb
->preds
) < 2
2280 && join_bb
!= EXIT_BLOCK_PTR
)
2282 /* We can merge the JOIN. */
2283 if (combo_bb
->global_live_at_end
)
2284 COPY_REG_SET (combo_bb
->global_live_at_end
,
2285 join_bb
->global_live_at_end
);
2287 merge_blocks (combo_bb
, join_bb
);
2292 /* We cannot merge the JOIN. */
2294 /* The outgoing edge for the current COMBO block should already
2295 be correct. Verify this. */
2296 if (EDGE_COUNT (combo_bb
->succs
) > 1
2297 || EDGE_SUCC (combo_bb
, 0)->dest
!= join_bb
)
2300 /* Remove the jump and cruft from the end of the COMBO block. */
2301 if (join_bb
!= EXIT_BLOCK_PTR
)
2302 tidy_fallthru_edge (EDGE_SUCC (combo_bb
, 0));
2305 num_updated_if_blocks
++;
2308 /* Find a block ending in a simple IF condition and try to transform it
2309 in some way. When converting a multi-block condition, put the new code
2310 in the first such block and delete the rest. Return a pointer to this
2311 first block if some transformation was done. Return NULL otherwise. */
2314 find_if_header (basic_block test_bb
, int pass
)
2316 ce_if_block_t ce_info
;
2320 /* The kind of block we're looking for has exactly two successors. */
2321 if (EDGE_COUNT (test_bb
->succs
) != 2)
2324 then_edge
= EDGE_SUCC (test_bb
, 0);
2325 else_edge
= EDGE_SUCC (test_bb
, 1);
2327 /* Neither edge should be abnormal. */
2328 if ((then_edge
->flags
& EDGE_COMPLEX
)
2329 || (else_edge
->flags
& EDGE_COMPLEX
))
2332 /* Nor exit the loop. */
2333 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2334 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2337 /* The THEN edge is canonically the one that falls through. */
2338 if (then_edge
->flags
& EDGE_FALLTHRU
)
2340 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2343 else_edge
= then_edge
;
2347 /* Otherwise this must be a multiway branch of some sort. */
2350 memset (&ce_info
, '\0', sizeof (ce_info
));
2351 ce_info
.test_bb
= test_bb
;
2352 ce_info
.then_bb
= then_edge
->dest
;
2353 ce_info
.else_bb
= else_edge
->dest
;
2354 ce_info
.pass
= pass
;
2356 #ifdef IFCVT_INIT_EXTRA_FIELDS
2357 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2360 if (find_if_block (&ce_info
))
2363 if (HAVE_trap
&& HAVE_conditional_trap
2364 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2367 if (dom_computed
[CDI_POST_DOMINATORS
] >= DOM_NO_FAST_QUERY
2368 && (! HAVE_conditional_execution
|| reload_completed
))
2370 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2372 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2380 fprintf (dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2381 return ce_info
.test_bb
;
2384 /* Return true if a block has two edges, one of which falls through to the next
2385 block, and the other jumps to a specific block, so that we can tell if the
2386 block is part of an && test or an || test. Returns either -1 or the number
2387 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2390 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2393 int fallthru_p
= FALSE
;
2400 if (!cur_bb
|| !target_bb
)
2403 /* If no edges, obviously it doesn't jump or fallthru. */
2404 if (EDGE_COUNT (cur_bb
->succs
) == 0)
2407 FOR_EACH_EDGE (cur_edge
, ei
, cur_bb
->succs
)
2409 if (cur_edge
->flags
& EDGE_COMPLEX
)
2410 /* Anything complex isn't what we want. */
2413 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2416 else if (cur_edge
->dest
== target_bb
)
2423 if ((jump_p
& fallthru_p
) == 0)
2426 /* Don't allow calls in the block, since this is used to group && and ||
2427 together for conditional execution support. ??? we should support
2428 conditional execution support across calls for IA-64 some day, but
2429 for now it makes the code simpler. */
2430 end
= BB_END (cur_bb
);
2431 insn
= BB_HEAD (cur_bb
);
2433 while (insn
!= NULL_RTX
)
2440 && GET_CODE (PATTERN (insn
)) != USE
2441 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2447 insn
= NEXT_INSN (insn
);
2453 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2454 block. If so, we'll try to convert the insns to not require the branch.
2455 Return TRUE if we were successful at converting the block. */
2458 find_if_block (struct ce_if_block
* ce_info
)
2460 basic_block test_bb
= ce_info
->test_bb
;
2461 basic_block then_bb
= ce_info
->then_bb
;
2462 basic_block else_bb
= ce_info
->else_bb
;
2463 basic_block join_bb
= NULL_BLOCK
;
2468 ce_info
->last_test_bb
= test_bb
;
2470 /* Discover if any fall through predecessors of the current test basic block
2471 were && tests (which jump to the else block) or || tests (which jump to
2473 if (HAVE_conditional_execution
&& reload_completed
2474 && EDGE_COUNT (test_bb
->preds
) == 1
2475 && EDGE_PRED (test_bb
, 0)->flags
== EDGE_FALLTHRU
)
2477 basic_block bb
= EDGE_PRED (test_bb
, 0)->src
;
2478 basic_block target_bb
;
2479 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2482 /* Determine if the preceding block is an && or || block. */
2483 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2485 ce_info
->and_and_p
= TRUE
;
2486 target_bb
= else_bb
;
2488 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2490 ce_info
->and_and_p
= FALSE
;
2491 target_bb
= then_bb
;
2494 target_bb
= NULL_BLOCK
;
2496 if (target_bb
&& n_insns
<= max_insns
)
2498 int total_insns
= 0;
2501 ce_info
->last_test_bb
= test_bb
;
2503 /* Found at least one && or || block, look for more. */
2506 ce_info
->test_bb
= test_bb
= bb
;
2507 total_insns
+= n_insns
;
2510 if (EDGE_COUNT (bb
->preds
) != 1)
2513 bb
= EDGE_PRED (bb
, 0)->src
;
2514 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2516 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
2518 ce_info
->num_multiple_test_blocks
= blocks
;
2519 ce_info
->num_multiple_test_insns
= total_insns
;
2521 if (ce_info
->and_and_p
)
2522 ce_info
->num_and_and_blocks
= blocks
;
2524 ce_info
->num_or_or_blocks
= blocks
;
2528 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2529 other than any || blocks which jump to the THEN block. */
2530 if ((EDGE_COUNT (then_bb
->preds
) - ce_info
->num_or_or_blocks
) != 1)
2533 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
2534 FOR_EACH_EDGE (cur_edge
, ei
, then_bb
->preds
)
2536 if (cur_edge
->flags
& EDGE_COMPLEX
)
2540 FOR_EACH_EDGE (cur_edge
, ei
, else_bb
->preds
)
2542 if (cur_edge
->flags
& EDGE_COMPLEX
)
2546 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2547 if (EDGE_COUNT (then_bb
->succs
) > 0
2548 && (EDGE_COUNT (then_bb
->succs
) > 1
2549 || (EDGE_SUCC (then_bb
, 0)->flags
& EDGE_COMPLEX
)
2550 || (flow2_completed
&& tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
2553 /* If the THEN block has no successors, conditional execution can still
2554 make a conditional call. Don't do this unless the ELSE block has
2555 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2556 Check for the last insn of the THEN block being an indirect jump, which
2557 is listed as not having any successors, but confuses the rest of the CE
2558 code processing. ??? we should fix this in the future. */
2559 if (EDGE_COUNT (then_bb
->succs
) == 0)
2561 if (EDGE_COUNT (else_bb
->preds
) == 1)
2563 rtx last_insn
= BB_END (then_bb
);
2566 && NOTE_P (last_insn
)
2567 && last_insn
!= BB_HEAD (then_bb
))
2568 last_insn
= PREV_INSN (last_insn
);
2571 && JUMP_P (last_insn
)
2572 && ! simplejump_p (last_insn
))
2576 else_bb
= NULL_BLOCK
;
2582 /* If the THEN block's successor is the other edge out of the TEST block,
2583 then we have an IF-THEN combo without an ELSE. */
2584 else if (EDGE_SUCC (then_bb
, 0)->dest
== else_bb
)
2587 else_bb
= NULL_BLOCK
;
2590 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2591 has exactly one predecessor and one successor, and the outgoing edge
2592 is not complex, then we have an IF-THEN-ELSE combo. */
2593 else if (EDGE_COUNT (else_bb
->succs
) == 1
2594 && EDGE_SUCC (then_bb
, 0)->dest
== EDGE_SUCC (else_bb
, 0)->dest
2595 && EDGE_COUNT (else_bb
->preds
) == 1
2596 && ! (EDGE_SUCC (else_bb
, 0)->flags
& EDGE_COMPLEX
)
2597 && ! (flow2_completed
&& tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
2598 join_bb
= EDGE_SUCC (else_bb
, 0)->dest
;
2600 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2604 num_possible_if_blocks
++;
2609 "\nIF-THEN%s block found, pass %d, start block %d "
2610 "[insn %d], then %d [%d]",
2611 (else_bb
) ? "-ELSE" : "",
2614 BB_HEAD (test_bb
) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
2616 BB_HEAD (then_bb
) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
2619 fprintf (dump_file
, ", else %d [%d]",
2621 BB_HEAD (else_bb
) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
2623 fprintf (dump_file
, ", join %d [%d]",
2625 BB_HEAD (join_bb
) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
2627 if (ce_info
->num_multiple_test_blocks
> 0)
2628 fprintf (dump_file
, ", %d %s block%s last test %d [%d]",
2629 ce_info
->num_multiple_test_blocks
,
2630 (ce_info
->and_and_p
) ? "&&" : "||",
2631 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
2632 ce_info
->last_test_bb
->index
,
2633 ((BB_HEAD (ce_info
->last_test_bb
))
2634 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
2637 fputc ('\n', dump_file
);
2640 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2641 first condition for free, since we've already asserted that there's a
2642 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2643 we checked the FALLTHRU flag, those are already adjacent to the last IF
2645 /* ??? As an enhancement, move the ELSE block. Have to deal with
2646 BLOCK notes, if by no other means than aborting the merge if they
2647 exist. Sticky enough I don't want to think about it now. */
2649 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
2651 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
2659 /* Do the real work. */
2660 ce_info
->else_bb
= else_bb
;
2661 ce_info
->join_bb
= join_bb
;
2663 return process_if_block (ce_info
);
2666 /* Convert a branch over a trap, or a branch
2667 to a trap, into a conditional trap. */
2670 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
2672 basic_block then_bb
= then_edge
->dest
;
2673 basic_block else_bb
= else_edge
->dest
;
2674 basic_block other_bb
, trap_bb
;
2675 rtx trap
, jump
, cond
, cond_earliest
, seq
;
2678 /* Locate the block with the trap instruction. */
2679 /* ??? While we look for no successors, we really ought to allow
2680 EH successors. Need to fix merge_if_block for that to work. */
2681 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
2682 trap_bb
= then_bb
, other_bb
= else_bb
;
2683 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
2684 trap_bb
= else_bb
, other_bb
= then_bb
;
2690 fprintf (dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
2691 test_bb
->index
, trap_bb
->index
);
2694 /* If this is not a standard conditional jump, we can't parse it. */
2695 jump
= BB_END (test_bb
);
2696 cond
= noce_get_condition (jump
, &cond_earliest
);
2700 /* If the conditional jump is more than just a conditional jump, then
2701 we can not do if-conversion on this block. */
2702 if (! onlyjump_p (jump
))
2705 /* We must be comparing objects whose modes imply the size. */
2706 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2709 /* Reverse the comparison code, if necessary. */
2710 code
= GET_CODE (cond
);
2711 if (then_bb
== trap_bb
)
2713 code
= reversed_comparison_code (cond
, jump
);
2714 if (code
== UNKNOWN
)
2718 /* Attempt to generate the conditional trap. */
2719 seq
= gen_cond_trap (code
, XEXP (cond
, 0),
2721 TRAP_CODE (PATTERN (trap
)));
2727 /* Emit the new insns before cond_earliest. */
2728 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
2730 /* Delete the trap block if possible. */
2731 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2732 if (EDGE_COUNT (trap_bb
->preds
) == 0)
2733 delete_basic_block (trap_bb
);
2735 /* If the non-trap block and the test are now adjacent, merge them.
2736 Otherwise we must insert a direct branch. */
2737 if (test_bb
->next_bb
== other_bb
)
2739 struct ce_if_block new_ce_info
;
2741 memset (&new_ce_info
, '\0', sizeof (new_ce_info
));
2742 new_ce_info
.test_bb
= test_bb
;
2743 new_ce_info
.then_bb
= NULL
;
2744 new_ce_info
.else_bb
= NULL
;
2745 new_ce_info
.join_bb
= other_bb
;
2746 merge_if_block (&new_ce_info
);
2752 lab
= JUMP_LABEL (jump
);
2753 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2754 LABEL_NUSES (lab
) += 1;
2755 JUMP_LABEL (newjump
) = lab
;
2756 emit_barrier_after (newjump
);
2764 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2768 block_has_only_trap (basic_block bb
)
2772 /* We're not the exit block. */
2773 if (bb
== EXIT_BLOCK_PTR
)
2776 /* The block must have no successors. */
2777 if (EDGE_COUNT (bb
->succs
) > 0)
2780 /* The only instruction in the THEN block must be the trap. */
2781 trap
= first_active_insn (bb
);
2782 if (! (trap
== BB_END (bb
)
2783 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2784 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2790 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2791 transformable, but not necessarily the other. There need be no
2794 Return TRUE if we were successful at converting the block.
2796 Cases we'd like to look at:
2799 if (test) goto over; // x not live
2807 if (! test) goto label;
2810 if (test) goto E; // x not live
2824 (3) // This one's really only interesting for targets that can do
2825 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2826 // it results in multiple branches on a cache line, which often
2827 // does not sit well with predictors.
2829 if (test1) goto E; // predicted not taken
2845 (A) Don't do (2) if the branch is predicted against the block we're
2846 eliminating. Do it anyway if we can eliminate a branch; this requires
2847 that the sole successor of the eliminated block postdominate the other
2850 (B) With CE, on (3) we can steal from both sides of the if, creating
2859 Again, this is most useful if J postdominates.
2861 (C) CE substitutes for helpful life information.
2863 (D) These heuristics need a lot of work. */
2865 /* Tests for case 1 above. */
2868 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2870 basic_block then_bb
= then_edge
->dest
;
2871 basic_block else_bb
= else_edge
->dest
, new_bb
;
2874 /* If we are partitioning hot/cold basic blocks, we don't want to
2875 mess up unconditional or indirect jumps that cross between hot
2878 Basic block partitioning may result in some jumps that appear to
2879 be optimizable (or blocks that appear to be mergeable), but which really
2880 must be left untouched (they are required to make it safely across
2881 partition boundaries). See the comments at the top of
2882 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2884 if (flag_reorder_blocks_and_partition
2885 && ((BB_END (then_bb
)
2886 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2887 || (BB_END (else_bb
)
2888 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2892 /* THEN has one successor. */
2893 if (EDGE_COUNT (then_bb
->succs
) != 1)
2896 /* THEN does not fall through, but is not strange either. */
2897 if (EDGE_SUCC (then_bb
, 0)->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2900 /* THEN has one predecessor. */
2901 if (EDGE_COUNT (then_bb
->preds
) != 1)
2904 /* THEN must do something. */
2905 if (forwarder_block_p (then_bb
))
2908 num_possible_if_blocks
++;
2911 "\nIF-CASE-1 found, start %d, then %d\n",
2912 test_bb
->index
, then_bb
->index
);
2914 /* THEN is small. */
2915 if (! cheap_bb_rtx_cost_p (then_bb
, COSTS_N_INSNS (BRANCH_COST
)))
2918 /* Registers set are dead, or are predicable. */
2919 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2920 EDGE_SUCC (then_bb
, 0)->dest
, 1))
2923 /* Conversion went ok, including moving the insns and fixing up the
2924 jump. Adjust the CFG to match. */
2926 bitmap_ior (test_bb
->global_live_at_end
,
2927 else_bb
->global_live_at_start
,
2928 then_bb
->global_live_at_end
);
2930 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
), else_bb
);
2931 then_bb_index
= then_bb
->index
;
2932 delete_basic_block (then_bb
);
2934 /* Make rest of code believe that the newly created block is the THEN_BB
2935 block we removed. */
2938 new_bb
->index
= then_bb_index
;
2939 BASIC_BLOCK (then_bb_index
) = new_bb
;
2940 /* Since the fallthru edge was redirected from test_bb to new_bb,
2941 we need to ensure that new_bb is in the same partition as
2942 test bb (you can not fall through across section boundaries). */
2943 BB_COPY_PARTITION (new_bb
, test_bb
);
2945 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2949 num_updated_if_blocks
++;
2954 /* Test for case 2 above. */
2957 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2959 basic_block then_bb
= then_edge
->dest
;
2960 basic_block else_bb
= else_edge
->dest
;
2964 /* If we are partitioning hot/cold basic blocks, we don't want to
2965 mess up unconditional or indirect jumps that cross between hot
2968 Basic block partitioning may result in some jumps that appear to
2969 be optimizable (or blocks that appear to be mergeable), but which really
2970 must be left untouched (they are required to make it safely across
2971 partition boundaries). See the comments at the top of
2972 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2974 if (flag_reorder_blocks_and_partition
2975 && ((BB_END (then_bb
)
2976 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2977 || (BB_END (else_bb
)
2978 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2982 /* ELSE has one successor. */
2983 if (EDGE_COUNT (else_bb
->succs
) != 1)
2986 else_succ
= EDGE_SUCC (else_bb
, 0);
2988 /* ELSE outgoing edge is not complex. */
2989 if (else_succ
->flags
& EDGE_COMPLEX
)
2992 /* ELSE has one predecessor. */
2993 if (EDGE_COUNT (else_bb
->preds
) != 1)
2996 /* THEN is not EXIT. */
2997 if (then_bb
->index
< 0)
3000 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3001 note
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
3002 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
3004 else if (else_succ
->dest
->index
< 0
3005 || dominated_by_p (CDI_POST_DOMINATORS
, then_bb
,
3011 num_possible_if_blocks
++;
3014 "\nIF-CASE-2 found, start %d, else %d\n",
3015 test_bb
->index
, else_bb
->index
);
3017 /* ELSE is small. */
3018 if (! cheap_bb_rtx_cost_p (else_bb
, COSTS_N_INSNS (BRANCH_COST
)))
3021 /* Registers set are dead, or are predicable. */
3022 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
3025 /* Conversion went ok, including moving the insns and fixing up the
3026 jump. Adjust the CFG to match. */
3028 bitmap_ior (test_bb
->global_live_at_end
,
3029 then_bb
->global_live_at_start
,
3030 else_bb
->global_live_at_end
);
3032 delete_basic_block (else_bb
);
3035 num_updated_if_blocks
++;
3037 /* ??? We may now fallthru from one of THEN's successors into a join
3038 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3043 /* A subroutine of dead_or_predicable called through for_each_rtx.
3044 Return 1 if a memory is found. */
3047 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
3052 /* Used by the code above to perform the actual rtl transformations.
3053 Return TRUE if successful.
3055 TEST_BB is the block containing the conditional branch. MERGE_BB
3056 is the block containing the code to manipulate. NEW_DEST is the
3057 label TEST_BB should be branching to after the conversion.
3058 REVERSEP is true if the sense of the branch should be reversed. */
3061 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
3062 basic_block other_bb
, basic_block new_dest
, int reversep
)
3064 rtx head
, end
, jump
, earliest
= NULL_RTX
, old_dest
, new_label
= NULL_RTX
;
3066 jump
= BB_END (test_bb
);
3068 /* Find the extent of the real code in the merge block. */
3069 head
= BB_HEAD (merge_bb
);
3070 end
= BB_END (merge_bb
);
3073 head
= NEXT_INSN (head
);
3078 head
= end
= NULL_RTX
;
3081 head
= NEXT_INSN (head
);
3088 head
= end
= NULL_RTX
;
3091 end
= PREV_INSN (end
);
3094 /* Disable handling dead code by conditional execution if the machine needs
3095 to do anything funny with the tests, etc. */
3096 #ifndef IFCVT_MODIFY_TESTS
3097 if (HAVE_conditional_execution
)
3099 /* In the conditional execution case, we have things easy. We know
3100 the condition is reversible. We don't have to check life info
3101 because we're going to conditionally execute the code anyway.
3102 All that's left is making sure the insns involved can actually
3107 cond
= cond_exec_get_condition (jump
);
3111 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
3113 prob_val
= XEXP (prob_val
, 0);
3117 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
3120 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
3123 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
3126 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
3135 /* In the non-conditional execution case, we have to verify that there
3136 are no trapping operations, no calls, no references to memory, and
3137 that any registers modified are dead at the branch site. */
3139 rtx insn
, cond
, prev
;
3140 regset merge_set
, tmp
, test_live
, test_set
;
3141 struct propagate_block_info
*pbi
;
3142 unsigned i
, fail
= 0;
3145 /* Check for no calls or trapping operations. */
3146 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
3152 if (may_trap_p (PATTERN (insn
)))
3155 /* ??? Even non-trapping memories such as stack frame
3156 references must be avoided. For stores, we collect
3157 no lifetime info; for reads, we'd have to assert
3158 true_dependence false against every store in the
3160 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
3167 if (! any_condjump_p (jump
))
3170 /* Find the extent of the conditional. */
3171 cond
= noce_get_condition (jump
, &earliest
);
3176 MERGE_SET = set of registers set in MERGE_BB
3177 TEST_LIVE = set of registers live at EARLIEST
3178 TEST_SET = set of registers set between EARLIEST and the
3179 end of the block. */
3181 tmp
= ALLOC_REG_SET (®_obstack
);
3182 merge_set
= ALLOC_REG_SET (®_obstack
);
3183 test_live
= ALLOC_REG_SET (®_obstack
);
3184 test_set
= ALLOC_REG_SET (®_obstack
);
3186 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3187 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3188 since we've already asserted that MERGE_BB is small. */
3189 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
3191 /* For small register class machines, don't lengthen lifetimes of
3192 hard registers before reload. */
3193 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
3195 EXECUTE_IF_SET_IN_BITMAP (merge_set
, 0, i
, bi
)
3197 if (i
< FIRST_PSEUDO_REGISTER
3199 && ! global_regs
[i
])
3204 /* For TEST, we're interested in a range of insns, not a whole block.
3205 Moreover, we're interested in the insns live from OTHER_BB. */
3207 COPY_REG_SET (test_live
, other_bb
->global_live_at_start
);
3208 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
3211 for (insn
= jump
; ; insn
= prev
)
3213 prev
= propagate_one_insn (pbi
, insn
);
3214 if (insn
== earliest
)
3218 free_propagate_block_info (pbi
);
3220 /* We can perform the transformation if
3221 MERGE_SET & (TEST_SET | TEST_LIVE)
3223 TEST_SET & merge_bb->global_live_at_start
3226 if (bitmap_intersect_p (test_set
, merge_set
)
3227 || bitmap_intersect_p (test_live
, merge_set
)
3228 || bitmap_intersect_p (test_set
, merge_bb
->global_live_at_start
))
3232 FREE_REG_SET (merge_set
);
3233 FREE_REG_SET (test_live
);
3234 FREE_REG_SET (test_set
);
3241 /* We don't want to use normal invert_jump or redirect_jump because
3242 we don't want to delete_insn called. Also, we want to do our own
3243 change group management. */
3245 old_dest
= JUMP_LABEL (jump
);
3246 if (other_bb
!= new_dest
)
3248 new_label
= block_label (new_dest
);
3250 ? ! invert_jump_1 (jump
, new_label
)
3251 : ! redirect_jump_1 (jump
, new_label
))
3255 if (! apply_change_group ())
3258 if (other_bb
!= new_dest
)
3261 LABEL_NUSES (old_dest
) -= 1;
3263 LABEL_NUSES (new_label
) += 1;
3264 JUMP_LABEL (jump
) = new_label
;
3266 invert_br_probabilities (jump
);
3268 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3271 gcov_type count
, probability
;
3272 count
= BRANCH_EDGE (test_bb
)->count
;
3273 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3274 FALLTHRU_EDGE (test_bb
)->count
= count
;
3275 probability
= BRANCH_EDGE (test_bb
)->probability
;
3276 BRANCH_EDGE (test_bb
)->probability
3277 = FALLTHRU_EDGE (test_bb
)->probability
;
3278 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3279 update_br_prob_note (test_bb
);
3283 /* Move the insns out of MERGE_BB to before the branch. */
3286 if (end
== BB_END (merge_bb
))
3287 BB_END (merge_bb
) = PREV_INSN (head
);
3289 if (squeeze_notes (&head
, &end
))
3292 reorder_insns (head
, end
, PREV_INSN (earliest
));
3295 /* Remove the jump and edge if we can. */
3296 if (other_bb
== new_dest
)
3299 remove_edge (BRANCH_EDGE (test_bb
));
3300 /* ??? Can't merge blocks here, as then_bb is still in use.
3301 At minimum, the merge will get done just before bb-reorder. */
3311 /* Main entry point for all if-conversion. */
3314 if_convert (int x_life_data_ok
)
3319 num_possible_if_blocks
= 0;
3320 num_updated_if_blocks
= 0;
3321 num_true_changes
= 0;
3322 life_data_ok
= (x_life_data_ok
!= 0);
3324 if ((! targetm
.cannot_modify_jumps_p ())
3325 && (!flag_reorder_blocks_and_partition
|| !no_new_pseudos
3326 || !targetm
.have_named_sections
))
3327 mark_loop_exit_edges ();
3329 /* Compute postdominators if we think we'll use them. */
3330 if (HAVE_conditional_execution
|| life_data_ok
)
3331 calculate_dominance_info (CDI_POST_DOMINATORS
);
3336 /* Go through each of the basic blocks looking for things to convert. If we
3337 have conditional execution, we make multiple passes to allow us to handle
3338 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3342 cond_exec_changed_p
= FALSE
;
3345 #ifdef IFCVT_MULTIPLE_DUMPS
3346 if (dump_file
&& pass
> 1)
3347 fprintf (dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3353 while ((new_bb
= find_if_header (bb
, pass
)))
3357 #ifdef IFCVT_MULTIPLE_DUMPS
3358 if (dump_file
&& cond_exec_changed_p
)
3359 print_rtl_with_bb (dump_file
, get_insns ());
3362 while (cond_exec_changed_p
);
3364 #ifdef IFCVT_MULTIPLE_DUMPS
3366 fprintf (dump_file
, "\n\n========== no more changes\n");
3369 free_dominance_info (CDI_POST_DOMINATORS
);
3374 clear_aux_for_blocks ();
3376 /* Rebuild life info for basic blocks that require it. */
3377 if (num_true_changes
&& life_data_ok
)
3379 /* If we allocated new pseudos, we must resize the array for sched1. */
3380 if (max_regno
< max_reg_num ())
3382 max_regno
= max_reg_num ();
3383 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3385 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3386 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3387 | PROP_KILL_DEAD_CODE
);
3390 /* Write the final stats. */
3391 if (dump_file
&& num_possible_if_blocks
> 0)
3394 "\n%d possible IF blocks searched.\n",
3395 num_possible_if_blocks
);
3397 "%d IF blocks converted.\n",
3398 num_updated_if_blocks
);
3400 "%d true changes made.\n\n\n",
3404 #ifdef ENABLE_CHECKING
3405 verify_flow_info ();